kill_these

Things that I would like to explicitely discourage in our documentation
(with a nice threat of deprecation):

What: Alternative array syntax
Kill: $foo{'bar'}
Instead: $foo['bar']

What: PHP4-style property declaration
Kill: var $foo;
Instead: public $foo;

What: PHP4-style constructor
Kill: class Foo { function Foo() {} }
Instead: class Foo { function __construct() {} }

What: Weird string interpolation syntax (1)
Kill: "a ${foo} b"
Instead: "a $foo b"

What: Weird string interpolation syntax (2)
Kill: "a ${foo['bar']} b"
Instead: "a {$foo['bar']} b" or "a $foo[bar] b"

As pointed out by @bwoebi, there is also:

What: Frivolous case seperator
Kill: case "value";
Instead: case "value":